EMBRYOLOGICAL STUDIES IN CANADIAN REPRESENTATIVES OF THE TRIBE RHINANTHEAE, SCROPHULARIACEAE

1963 ◽  
Vol 41 (2) ◽  
pp. 267-302 ◽  
Author(s):  
Govindappa D. Arekal
Keyword(s):  
Ab Initio ◽  
Embryo Development ◽  
Seed Coat ◽  
Nuclear Division ◽  
Vertical Wall ◽  
Embryo Sac ◽  
Intercellular Spaces ◽  
Chalazal Haustorium ◽  
Thin Walled ◽  
Polygonum Persicaria

Descriptions are given of the ovary and ovules, megasporogenesis, embryo sac, endosperm, embryo, and seed coat structure of Euphrasia arctica Lange, Orthocarpus luteus Nutt., and Melampyrum lineare Desr. Although the ovary is usually bicarpellary, syncarpous, and bilocular with axile placentation in the tribe, a tendency toward unilocularity and parietal placentation occurs in Orthocarpus luteus. The number of ovules is reduced to four in Melampyrum lineare. Development of the embryo sac is of the monosporic eight-nucleate type in Euphrasia arctica and Orthocarpus luteus, but is tetrasporic and seven-nucleate in Melampyrum lineare. No fusion of polar nuclei occurs in the latter. The endosperm is ab initio cellular. Nuclear division in the primary micropylar chamber is followed by a vertical wall which remains incomplete. Aggressive haustoria develop at opposite ends of the endosperm. The chalazal haustorium is unicellular and binucleate. The micropylar haustorium is incompletely bicelled, with four nuclei in E. arctica and M. lineare and two nuclei in O. luteus. In M. lineare six to eight tube-like processes develop from the micropylar haustorium of which one usually enlarges and enters the funicle. The endosperm proper is generally uniform in E. arctica and O. luteus, but in M. lineare it becomes differentiated into three regions, the massive micropylar part consisting of cells with thickened, prominently pitted walls and the chalazal part of thin-walled cells with large intercellular spaces. Embryo development in E. arctica and O. luteus resembles that of Capsella bursa-pastoris, while development in M. lineare follows that of Polygonum persicaria. Embryologically Melampyrum lineare differs markedly from other members of the tribe.

DEVELOPMENT OF THE SEED AND FRUIT IN MELAMPYRUM NEMOROSUM L. AND M. ARVENSE L.

1965 ◽  
Vol 43 (12) ◽  
pp. 1511-1521 ◽  
Author(s):  
B. Tiagi
Keyword(s):  
Seed Coat ◽  
Embryo Sac ◽  
Developing Seed ◽  
Chalazal Haustorium ◽  
Meristematic Region ◽  
Micropylar Canal ◽  
Pass Through

The ovary is bilocular, with four massive axile placentae, each bearing a sessile hemianatropous, unitegmic, and tenuinucellate ovule. The innermost integumentary layer forms endothelium around the micropylar part of the embryo sac. The micropylar canal is surrounded by the micropylar tube, whereas the endothelium is hypodermal in this region. The endothelium and an adjacent meristematic region contribute to the growth of the integument. The endosperm is of the Brunella type described by K. Schnarf in 1929. The chalazal haustorium is a highly aggressive, two-nucleate chamber which becomes inactive and is filled with a haustorial chalazal endosperm. The two multinucleate micropylar haustorial cells give rise to many tubular extensions which pass through the micropylar tube, but only one reaches the placenta. The cells of the storage endosperm are pitted and thickened with hemicellulose. An opaque tanniferous zone of endosperm separates the storage endosperm from the chalazal endosperm. The embryo is small and straight, with two cotyledons and a hypocotyledonary region. The seed coat is feeble, one to three layered. The pericarp is many layered and cuticularized. The two innermost lignified layers form columns at the dorsal line of the two valves of the capsule, where it dehisces. The chalazal part of the developing seed absorbs nourishment directly from the pericarp.

Morphological peculiarities of seeds of some species of the genus Epipactis Zinn. (Orchidaceae Juss.) of Ukrainian flora

2019 ◽  
Vol 11 (1) ◽  
pp. 93-100
Author(s):  
T Ljubka ◽  
O Tsarenko ◽  
I Tymchenko
Keyword(s):  
Seed Coat ◽  
Cell Walls ◽  
Morphological Study ◽  
Population Level ◽  
Intercellular Spaces ◽  
Different Populations ◽  
Periclinal Walls ◽  
High Degree ◽  
Shape And Size ◽  
Generative Organs

The investigation of macro- and micromorphological peculiarities of seeds of four species of genus Epipactis (Orchidaceae) of Ukrainian flora were carried out. The genus Epipactis is difficult in the in in taxonomic terms and for its representatives are characterized by polymorphism of morphological features of vegetative and generative organs of plants and ability of species to hybridize. The aim of the research was to perform a comparative morphological study of seeds of E. helleborine, E. albensis, E. palustris, E. purpurata and to determine carpological features that could more accurately identify species at the stage of fruiting. A high degree of variation in the shape of the seeds in different populations within the species and overlap of most quantitative carpological characteristics of studied species are noted. There were no significant differences in micromorphological features of the structure of the testa at species or population level. The reticulate surface of the testa is characteristic of all species, the cells of testa are mostly elongated, penta-hexagonal, individual cells almost isodiametric-pentagonal. From the micropillary to the chalasal end, a noticeable change in the shape and size of the seed coat cells is not observed. There are no intercellular spaces, the anticlinal walls of adjacent cells are intergrown and the boundaries between them become invisible. The outer periclinal walls have a single, mainly longitudinal thin ribbed thickenings. Anticlinal cell walls are thick, dense, smooth. The longitudinal Anticlinal walls are almost straight, transverse - straight or sometimes curved in some cells. Epicuticular deposits on the periclinal walls are absent. It is concluded that the use of macro and micromorphological characteristics of seeds of these species for clearer diagnosis at the stage of fruiting is low informative.

scholarly journals Ontogenia de la semilla de Yucca periculosa (Agavaceae)

2017 ◽  
pp. 5
Author(s):  
Eduardo García-Villanueva ◽  
E. Mark Engleman
Keyword(s):  
Cell Wall ◽  
Embryo Development ◽  
Seed Coat ◽  
Outer Integument ◽  
Triangular Prism ◽  
Seed Shape ◽  
Food Reserve ◽  
Seed Maturity ◽  
Nuclear Development ◽  
Black Color

Seeds of several Yucca species have been studied by Arnott and Horner. They mainly studied the nature condition and stated that the extra-embryonic food reserve tissue is a perisperm. This paper provides ontogenic evidence that this tissue is an endosperm with nuclear development type. The seed shape is nearly a triangular prism less than 1 cm long, black color and the raphe groove is conspicuous. The seed coat is derived exclusively from the outer integument. The exotesta external periclinal cell wall appears with irregular thickness. Both mesotesta and endotesta grow irregularly inward the seed confering to the endosperm a ruminate appearance. Toward seed maturity, the inner integument tissues disappear, thus fusion between intertegumentary and tegmen-nucellar cuticles occurs; valuable ontogenic information is showed by the cuticles, due to its persistence in spite of its generative tissue disappearance. The embryo development increases until 10 weeks after anthesis, it is cylindric, folds like "S" and two thirds of its chalazal lenght correspond to the cotyledon.

Ovule and seed structure in Scolopia zeyheri (Scolopieae), with notes on the embryology of Salicaceae

Bothalia ◽  
2005 ◽  
Vol 35 (2) ◽  
pp. 175-183 ◽  
Author(s):  
E. M. A. Steyn ◽  
A. E. Van Wyk ◽  
G. F. Smith
Keyword(s):  
Microscopic Study ◽  
Seed Coat ◽  
Embryo Sac ◽  
Single Layer ◽  
Relevant Information ◽  
Seed Structure ◽  
Globular Embryo ◽  
Polygonum Type ◽  
Old World ◽  
Seed Characters

Scolopia zeyheri (Nees) Harv. is a widespread African tree and a member of the largest genus of the tropical Old World tribe Scolopieae (Salicaceae sensu lato). This light microscopic study is the first report on ovule and seed structure in the genus and the tribe. Ovules vary from four to six per ovary, are anatropous. crassinucellate. bitegmic and occur in an epitropous (rarely pleurotropous). median-parietal position in the unilocular, usually bicarpellate ovary. A very extensive nucellus cap. comprising nucellus epidermal derivatives and parietal tissue, characterizes the young ovule during mega- sporogenesis and megagametogenesis, but the chalazal nucellus is poorly developed. During meiosis. the micropvlar dyad cell degenerates early. The functional dyad cell forms two megaspores of which the chalazal one usually develops into a Polygonum-type embryo sac. At maturity, the micropylar end of the embryo sac is covered by the remnants of the nucellus epidermis, the parietal tissue having degenerated. The globular embryo has a short suspensor and lies in nuclear endosperm becoming cellular. The seed coat develops from both integuments, is tannimferous. has a glabrous surface with stomata and a single layer of exotegmic, longitudinal fibres.Results are compared with relevant information previously reported for genera in the tribes Flacourtieae. Samvdeae. Saliceae, Scyphostegiae and for Oncoha Forssk. (Salicaceae sensu lato). Embryologically Scolopia shows a number of ple- siomorphic features compared to other Salicaceae. For example, it lacks an extranucellar embryo sac. an apomorphic fea­ture in many Salicaceae. A summary of ovule and seed characters in Salicaceae sensu lato is given and contrasted with data available for Achariaceae  sensu lato. Embryological data broadly supports the reclassification of genera, traditionally referred to Flacourtiaceae. amongst Salicaceae sensu lato and Achariaceae sensu lato.

THE DEVELOPMENT OF THE BLUEBERRY SEED

1957 ◽  
Vol 35 (2) ◽  
pp. 139-153 ◽  
Author(s):  
Hugh P. Bell
Keyword(s):  
Seed Development ◽  
Seed Coat ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Homogeneous Plasma ◽  
Stage Of Development ◽  
Micropylar Endosperm ◽  
Mature Seeds ◽  
Number Of Seeds

Seed development was followed from fertilization to maturity. Pollen tubes required about 4 days to grow from stigma to ovule. In some plants, particularly bagged ones, nucellar cells remained alive and contents of the embryo sac degenerated. Many ovules did not develop. Seeds were counted and sorted in a random representative collection of 1075 berries. The average number of seeds per berry was 64.2. Of these 49.9 (or 77.7%) were imperfect. More complete pollination increased the percentage of normally developing ovules. Development of perfect seeds followed a familiar pattern. Unfamiliar features were noted as follows: 1. Degeneration of cells at both micropylar and chalazal ends resulted in a homogeneous plasma. This plasma formed strands across haustoria and almost completely surrounded the zygote. 2. Micropylar endosperm cells formed a dense plug. Developing embryos may have had difficulty in penetrating this plug. 3. Many embryos had died at some stage of development. 4. A conspicuous integumentary tapetum was present until the endosperm was about half its final size.Embryo development was the "soland" type. Mature seeds were "axile linear". Imperfect seeds were chiefly of two types: (a) medium sized and solid with middle integumentary layers lignified, or (b) small and collapsed with all tissues inside seed coat disintegrated. No imperfect seed had an embryo.

Anther, ovule, seed, and nucellar embryo development in Citrus sinensis cv. Valencia

1995 ◽  
Vol 73 (10) ◽  
pp. 1567-1582 ◽  
Author(s):  
Anna M. Koltunow ◽  
Kathleen Soltys ◽  
Nobumasa Nito ◽  
Stuart McClure
Keyword(s):  
Embryo Development ◽  
Fruit Development ◽  
Embryo Sac ◽  
Morphological Characteristics ◽  
Central Portion ◽  
Seed Formation ◽  
Nucellar Embryony ◽  
Nucellar Embryo ◽  
Unfertilized Ovules

'Valencia' orange, a commercially important cultivar of Citrus, forms polyembryonic seeds by an apomictic process called nucellar embryony in which many embryos initiate directly from nucellar cells surrounding the sexual embryo sac. We observed anther, ovule, seed, and fruit development in relation to nucellar embryo development in seeds and unfertilized ovules of 'Valencia'. Pollination and fertilization are required to set fruit in 'Valencia', and low seed set was found to be related to defects in both male and female gametogenesis. Nucellar embryo initial cells were evident histologically in ovules of flowers just prior to anthesis. However, in vitro culture of ovules from flowers at different prepollination stages showed that embryos could develop from ovules cultured as early as the binucleate stage of megagametogenesis in which nucellar initial cells were absent histologically. During fruit development, the timing and sequence of the early events of nucellar embryo formation were synchronous in seeds and unfertilized ovules, indicating a co-ordinated control of embryo development in spatially and developmentally distinct structures. In both developing seeds and unfertilized ovules, embryo initial cells first formed thick walls, which isolated them from surrounding maternal tissue. In later stages, the cell walls thinned in some initial cells and embryogenesis became asynchronous. Cleavage of embryogénie cells coincided with degenerative processes linked to embryo sac expansion in seeds and to a previously unreported, localized degeneration in the central portion of the nucellus in unfertilized ovules. Some initial cells never divided. Nucellar embryo development was restricted to the central portion of unfertilized ovules and to the micropylar region of seeds. Only fertilized ovules had the capacity to form mature polyembryonic seeds. In unfertilized ovules a specialized vascular structure formed linking developing embryos to the chalazal vasculature of the ovule. Embryo development arrested at the globular stage in unfertilized ovules and the integuments differentiated to form a seed coat. The timing of reproductive events described was linked to floral and fruit morphological characteristics to facilitate molecular characterization of nucellar embryogenesis and seed formation in this cultivar. Key words: Citrus, nucellar embryony, seed, ovule, apomixis.

scholarly journals From embryo sac to oil and protein bodies: embryo development in the model legume Medicago truncatula

2011 ◽  
Vol 193 (2) ◽  
pp. 327-338 ◽  
Author(s):  
Xin-Ding Wang ◽  
Youhong Song ◽  
Michael B. Sheahan ◽  
Manohar L. Garg ◽  
Ray J. Rose
Keyword(s):  
Embryo Development ◽  
Medicago Truncatula ◽  
Embryo Sac ◽  
Protein Bodies ◽  
Model Legume

scholarly journals Embryological studies on Anthemis tinctoria L.

2015 ◽  
Vol 46 (4) ◽  
pp. 547-557 ◽  
Author(s):  
K. Bijok ◽  
T. Pawlak ◽  
B. Kreńska
Keyword(s):  
Chromosome Number ◽  
Embryo Development ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Natural Habitats ◽  
Antipodal Cells

The chromosome number of <i>Anthemis tinctoria</i> from natural habitats in Poland is n=9. The development of pollen grains is normal. The embryo-sac is of tetrasporic type and the number of antipodal cells is seven, all derived from one-cellular archespore. The embryo development is of Aster type and the endosperm is of nuclear type.

scholarly journals Morphology of Postpollination Fruit Abortion in Pecan

1995 ◽  
Vol 120 (3) ◽  
pp. 446-453
Author(s):  
I.E. Yates ◽  
Darrell Sparks
Keyword(s):  
Embryo Development ◽  
Direct Evidence ◽  
Embryo Sac ◽  
Growing Season ◽  
Carya Illinoensis ◽  
Egg Apparatus ◽  
Cellular Endosperm ◽  
Fruit Abortion

Anatomy of normal and abortive fruit was compared at each of the three postpollination fruit drops characteristic of pecan [Carya illinoensis (Wangenh.) C. Koch]. Size differences between normal and abortive fruit decreased during the growing season, but differences in ovule size between normal and abortive fruit increased. During Drop II, normal and abortive fruit had an integument enclosing a massive nucellus in which an embryo sac was embedded, but embryo sac shape and constituents differed. Embryo sacs were distended in normal fruit and contained a definitive zygote as evidence of fertilization, i.e., union of egg and sperm. In contrast, embryo sacs in abortive fruit were shriveled and contained an egg apparatus as in unfertilized distillate flowers. During Drop III, normal and abortive fruit had a similar multicellular embryo. The nucellus in normal fruit was reduced to a cap at the micropyle region and cellular endosperm was evident. In contrast, the nucellus in abortive fruit was abundant and cellular endosperm was not evident. During Drop IV, embryo development in abortive fruit lagged behind that of normal fruit. Thus, we present the first direct evidence that aborted pecans deviate from normal fruit by an absence of a zygote at Drop II, a deficiency in cellular endosperm at Drop III, and a delay in embryo development at Drop IV.

scholarly journals Embriología de Erythroxylum havanense Jacq. (Erythroxylaceae)

2017 ◽  
pp. 25
Author(s):  
Sonia Vázquez-Santana ◽  
César A. Domínguez ◽  
Judith Márquez-Guzmán
Keyword(s):  
Seed Coat ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Reproductive Structures ◽  
Exine Sculpturing ◽  
Erythroxylum Havanense ◽  
Mature Anther

We studied the development of reproductive structures in pin and thrum morphs of Erythroxylum havanense. The young anther wall consists of an epidermis, endothecium , 1-3 middle layers anda binucleate secretory tapetum. The mature anther wall has only two layers: epidermis and endothecium. Microspore tetrads are tetrahedral or isobilateral. Mature pollen grains are tricolporate, bicellular and contain starch grains. Exine sculpturing is verrugate in thrum pollen and reticulate in pin pollen. The ovule is sessile, pendulous, anatropous, bitegmic and crassinucellate. The embryo sac is heptacellular. An endothelium is differentiated. The endosperm development is nuclear, and the basal part of the nucellus persists during early endosperm development. Both integuments form the seed coat.

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